The invention disclosed herein pertains to an endoscope used to visualize the urinary system. As shown in FIG. 1, kidneys 13 of the human body are connected to a bladder 9 by very narrow ducts called ureters 11 The openings of the ureters 11 into urinary bladder 9 are about 1 to 4 mm wide. Bladder 9 is partially surrounded from behind by pelvis 15 which serves as a protective shield for the bladder. The natural flow of body fluids is from the kidneys 13 through ureters 11 into bladder area 9 and is discharged from the body through urethra 17. The opening of the urethra to release fluids from the body is about 5 mm to 10 mm wide.
Urinary bladder stones 8 and kidney stones 7 have been known to become lodged in the bladder 9 and ureters 11 as well as in calyxes 5 of the kidney 13 respectively. This causes blockage of flowing body fluids and is very painful. Various medical devices have been developed to remove bladder stones 8, and/or kidney stones 7. The devices for removing the latter are pertinent to the general subject matter of the present invention.
The medical devices which have been developed to remove kidney stones generally involve a multi-channeled device called a ureteroscope. The ureteroscope is positioned within the body (i.e. urethra 17, bladder 9 and ureter 11) and has working channels which provide access to and from the areas where kidney stones 7 are lodged. A typical ureteroscope is rigid along its length so as to enable axial and rotational translation in the urethra 17 and bladder 9 areas. Typically, the rigid ureteroscope is greater than 3 mm in diameter and therefore unable to fit through most openings into ureters 11 in their natural size. Ureters 11 can be mechanically dilated to accommodate the rigid ureteroscope This dilation is however traumatic to the body, even though it may not be symptomatically apparent. Even after entering the ureter 11, the rigid ureteroscope is unable to bend toward the kidney stones 7 lodged in calyxes 5 of kidneys 13. Furthermore, the tip end of the rigid ureteroscope tends to penetrate the surrounding body tissue during use and is therefore considered to be traumatic to the body.
A flexible ureteroscope has been developed to serve the same purpose as the rigid ureteroscope. The flexible ureteroscope is guided by a rigid cylindrical tube called a cystoscope which is positioned in the bladder 9 through the urethra 17. The flexible ureteroscope is inserted into the cystoscope which guides the flexible ureteroscope to the bladder 9 and into the ureter 11. The cystoscope is too large in diameter to enter the ureter 11. Thus, the flexible ureteroscope must be maneuvered past the end of the rigid cystoscope and into the opening of the ureter 11 from the bladder 9. This requires the user of the device to stabilize the rigid cystoscope while maneuvering the flexible ureteroscope from an end opposite the target end. Further, the flexible tube of the ureteroscope is so flexible that it tends to coil at the opening to the ureter 11 (especially when the opening is tight) once outside the end of the rigid cystoscope and is not easily maneuvered by the pushing action of the user from the opposite end. In addition, a rotational torque can not be easily transmitted to the target or tip end of the flexible ureteroscope. On the other hand the tip end of the flexible ureteroscope is less traumatic to the body than the tip end of the rigid ureteroscope.
Employed within a working channel of the flexible and/or rigid ureteroscopes are various mechanical accessories for engulfing and retrieving, or grasping and crushing kidney stones 7. Also, a rigid ultrasound probe for delivering ultrasound waves to break the kidney stones 7 has been developed to be employed in a working channel of a rigid ureteroscope. Further, an electrohydraulic generator has been developed to generate a spark at the tip end of a flexible or rigid ureteroscope to break target kidney stones 7 which are positioned adjacent to the tip end of the ureteroscope.
Recently, "extracorporeal acoustic shock wave" therapy has been used to break kidney stones into particles which are small enough to pass through the ureter and urethra by natural means. This therapy entails the immersion of the patient in a bath of water. Shock waves are generated in the water and focused toward the areas where target kidney stones are lodged. The waves penetrate the body from the outside and break the target stones. However, such acoustic shock wave therapy or treatment does not affect kidney stones which are lodged in the lower region of ureters 11 and protected by the surrounding pelvis 15.
More recently, the Candela Laser Corporation dye laser has been developed to apply a photoacoustic effect to kidney stones 7 which are lodged in areas protected by the pelvis 15 and in other areas. Such an effect breaks the stones into particles which are small enough to pass through the ureter and urethra.